Manufacture of insoles



Patented Nov. 3, 1931 UNITED STATES PATENT, OFFICE EIMER A. ELLIS, OF MEDFORD, MASSACHUSETTS, ASSIGNOR TO BOSTON BLACKING COM PANY, INQ, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS MANUFACTURE OF INSOLES Application filed November 8, 1929. Serial 1T0. 405,757.

This invention relates to the manufacture of insoles. The invention is herein illustrated with special reference to its application to the coating of fabric and to use of the fabric in reinforcing insoles, to cementcompd. sitions for use'in coating such fabric, and to fabric coated therewith.

It has long been a practice in the manufacture of shoes, particularly welt shoes, to reinforce insoles by cementing thereto a layer of duck, canvas or the like textile fabric material, the fabric being shaped to the sewing lip or rib of the insole to reinforce the lip,

thereby forming a more secure anchorage for the inseam stitches. The usual practice in the reinforcement of insoles has been to employ a strip of fabric of approximately the width of the insole, having several coats of thermoplastic material containing gutta percha or gutta siak. The coated strip had to be heated just prior to its application to the insole to render the coating tacky and had to be formed while hot to the lip of the insole in order to secure proper adhesion of the strip to the insole. The degree of heat required to put the material in the best con- 1 dition for use was rather critical and hence considerable skill and attention on the part of the operator were required in order to produce uniform results. The operator also lost considerable time in waiting for the material to heat up. Also, the strip was supplied to the operator in a roll and since the coating, even at ordinary temperatures, Was tacky, there was adhesion of the strip in the roll and it was therefore diflicult for the o erator to unwind the strip.

lVhen an insole reinforced by the described process was incorporated in a shoe and the shoe placed in the toe steamer to condition the box toe for the lasting operation, it was found that the steam was likely to cause the hold of the thermoplastic gutta percha or gutta siak coating on the insole to loosen and the reinforcing material to draw away from the insole, particularly at the lip or rib where.

adhesion was important. "None of the attemptsmade to mitigate this condition was entirely satisfactory. Furthermore, the coated material supplied to the shoe manu facturer was sometimes found unsuitable for use because of variations in the coating composition which made it too tacky or not tacky enough and even if the coated material worked satisfactorily when first received it was apt to deteriorate in a short time, es-

pecially in hot weather.

On the other hand, the attempts which have been made to develop a cold process which would meet with general approval on the part of shoe manufacturers have been unsuccessful. For example, a strip of duck was drawn through a cement applying device of usual construction by which a single coating y of ordinary fluid rubber cement containing a large proportion of solvent was applied to one side of the strip. In order for the coating to become tacky (instead of slimy) and thus suitable for use, a large part of the solvent in the cement on the strip was allowed to evaporate through exposure to the air. This exposure of the strip took up a large amount of space in the factory and waiting for the strip to dry consumed an impracticable.

amount of time. Moreover, the adhesion of the strip was inadequate because the coating was too thin. Attempts have also been made to use a strip having a permanent tacky coating much like that of surgeonsplaster. This material, however, if it had sufiicient tackinessto enable it to be satisfactorily used when cold for reinforcing insoles also had sufficient tackiness to cause it to adhere to itself in the roll so that pulling the strip off the roll was difficult and undesirably increased the labor of the operator and decreased the output.

In view of the foregoing and other con.- siderations, l have provided a novel method of coating fabric and of using such fabric in reinforcing insoles. In the practice of my preferred procedure I'use a suitable fabric, such as gem duck, coated in the web with a cold rubber cement composition containing rubber, a resin and a solvent and capable of being rendered permanently non-tacky upon volatilization of the solvent and consequent drying of the coating. Theweb is then heated to evaporate the solvent, thus rendering the coating non-tacky and the webis cut into strips and wound into rolls which, because the cement is non-tacky, can be easily unwound. a

The resin content of the coating composition employed for the first coating consists "preferably of Burgundy pitch (a resin the usual source of which is the Norway spruce, Pv'cea abz'es) in the proportion of one part pitch to three of rubber. A filler, such as zinc oxide, is preferably used to facilitate spreading of the composition, two parts of filler to one of pitch being satisfactory.

Prior to the use of a strip as reinforcing material, a coating of rubber cement composition is applied by the shoe manufacturer at room temperature and a portion of the strip is applied almost immediately to the insole which is to be reinforced. This coating, while it may advantageously be made up in general of ingredients similar to those used in the first coating, preferably has the ingredients in different proportions, for example the rubber, filler and resin may be in nearly equal amounts, the resin somewhat predominating. The proportion of solvent in this composition is relatively small so that a cement having a high viscosity is produced and having, because of the high resin content, the requisite tackiness. While rosin (colophony) or other resins may be used to produce a practicable degree of tackiness, I

ave found that in order to produce the requisite high degree of tackiness Burgundy pitch is particularly desirable as the resin content of the second coating. The solvent employed in the second coating is preferably one that will quickly evaporate substantially completely at ordinary room temperature, preferably a hydrocarbon solvent or naphtha which is substantially free from the higher boiling point hydrocarbonsusually found in solvent naphthas so that it quickly evaporates substantially completely. The composition for the se ond coating is applied to the strip while cold, that is at normal room temperature, the coating being very thick compared with the thickness of the first coat.

-.As soon as the highly viscous and heavy second coating is applied to the strip, the str1p is exposed to the air and the highly volatile solvent begins to evaporate from the exposed surface. At the same time the first coating is absorbing the solvent from the second coating so that in a very short time, in fact in a few seconds, sufficient solvent has been. removed from the second coating to render it tacky instead of slimy or slippery, and hence it is in suitable condition for the application to the insole. Since the two coatings are of a similar nature, the rubber solvent .absorbed by the first coating from the second coating softens the first coating so that the two coatings cohere and firm adhej ssion between strip and the insole is assured. (it:

While the coated strip is thus adapted for immediate use while the coating is fresh and i is preferably so used, the time during which invention the shoe manufacturer is saved the expense of heating the strip, the adhesion of the reinforcing material to the insole is not adversely affected by the subsequent toe steaming operation but rather is caused to adhere more firmly, and the loss due to deterioration of the coating on the coated strip by lapse of time is done away with. Because there is no heating and consequent shrinkage in length, a roll of a givenyardage will reinforce more insoles than will a roll of the same length having a coating adapted for use with the prior hot process and applied bythat process. Moreover, working conditions when the present method is practised are much improved over those incident to prior methods since objectionable heat and vapor are avoided.

In the drawings,

Fig. 1 illustrates the applying of a preliminary coating to the reinforcing material and drying it, a suitable coating apparatus being shown partly in longitudinal section and partly in elevation;

Fig. 2 illustrates the cutting of the coated Web into strips and the forming of the strips into rolls, suitable stripping and winding apparatus being shown partly in perspective and partly in section;

Fig. 3 illustrates the steps of applying a Fig. 4 illustrates the operation of formQ ing the cut-off portion of the material against the inner face of the rib of the insole and against the bottom of the insole, the figure being a perspective view of the insole, reinforcing material. and hand tool employed for the purpose; and

Fig. 5 illustrates the operation of further forming the reinforcing material to the insole and trimming off the'eXcess o'f reinforcing material flush with the outer edge of the rib of the insole, the figure being a view, partlyin section and partly in elevation, of the operating instrumentalities of an insole reinforcing machine.

in the illusrated method of reinforcing insoles in which acoating of cement is applied to a strip of precoated canvas and t e strip employed to reinforce insoles, the preliminary coating may be applied by apparatus such as that illustrated in Fig. 1. The duck, in a web 8 of usual width, is drawn from a supply 10 over a rubber-covered roll 12, the web .8 drawn from the supply being maintained under tension by a suitable friction device such as a cord 14 held frictionally against a pulley on the shaft of the supply roll 10 by a suitable weight 16. Over the rubber-covered roll 12 is a stripper 18 arranged for adjustment toward and from the roll by screws 20 arranged at theopposite ends of the stripper.

It has been found in practice that a suitable cement composition for usein applying the first coating may have the following composition: V Rubber Q (55 pounds Zinc oxide 41 pounds Burgundy pitch 22 pounds Naphtha 43 gallons The cement used in coating the material is contained in a receptacle 22 arranged on trunnions so that periodically a supply of cement 24 may be dumped on to the duck before it reaches the stripper, the motion of the duck carrying the cement 24 into the bite between the roll 12 and the stripper 18 and maintaining it there during the coating operation. At each end of the stripper 18 the roll and arranged so as to prevent the cement from spreading laterally beyond the edge of the web. After leaving the stripper the web 8 passes over a heat conducting supporting, plate 28 beneath which is arranged a series ofsteam pipes 30 by which the plate 28 and consequently the web are heated to dry the cement, that is, to drive oif the volatile rubber solvent which the cement contains. Over the steam pipes 30 is arranged a hood 32 for conducting 01f the vapor of the rubber solvent given off by the cement in the early sta es of the drying operation. Further drying of the cement after the web. fifl'laves the hood is effected by a series of steam pipes 34. The web then passes over a spreader bar 36, around a felt covered cylindrical roll 38 which is preferably power driven, and beneath a partition 40 which protects it at this stage from the heat of the steam pipes 30, 34. During the passage of the web beneath the partition 40 a blast of air is blown against its coated surface from an air duct 42 to cool and further dry the coating. The web is then Wound on a shaft 44 into a roll 46," the shaft 44 being also driven in any suitable manner to assist the roll 38 in drawing the web through the coating apparatus.

Since, in drying the first coating on the is a plate 26 fitted to the stripper and to' web, artificial heat is employed to" drive off.

the solvent, the nature of the solvent is relatively unimportant, 'it-being possible to employ the cheaper hydrocarbon solvents such as gasoline or low test naphtha with success.

The coating thus a plied is preferably quite thin, the objects 0 its use being to fill the pores of the duck so that it will not absorb toomuch of the second coating, to cement down the loose fibers of the duck, to prevent ravelling of the duck when it is cut into strips, and to afford a surface to which the second coating later applied will readily stick. Another important function of the first coating is to provide on the strip a ma 'iterial which will quickly absorb solvent from the second coating later applied to the strip,

thereby quickly rendering the second coating tacky, and which will prevent the cementing material in the solvent'from being absorbed suflicient pressure to cause the web to be cut into separate strips 52 which are wound'into separable rolls 54. Preferably the cutters at each end of the roll 48 are arranged ]ust insidethe selvage of the web so that the rough and irregular edges of the web will be re- 1.".

moved and each of the strips formed by the stripping machine will have straight edges and will be of uniform width. The dlscarded marginal portion which is removed from one side of the web is illustrated at 56 in Fig. 2, it being understood, of course, that there is a similar marginal portion removed from the opposite side of the web.

For the second and final coating of cement to be applied to the strips 52, the following I composition has been found suitable in practice Rubber 48 pounds Zinc oxide 48 pounds Burgundy pitch 60 pounds Naphtha (high test) 14 gallons The high test naphtha referred to in this composition is preferably thatwhich distills over between 165 F. and 238 F., the specific gravity of the naphtha being about B.

The second coating may be applied to the strips 52 by means of apparatus illustrated in Fig. 3. For this purpose I prefer to employ the coating apparatus disclosed in Letters Patent of the United States No. 1,771.388, granted July 22. 1930, on an application filed in the name of Russell K. Nash. One of the rolls-54 is suitably supported forrotation on a bracket 58 and passed beneath a body.,of

cement in a nozzle 62. By drawing the strip 52 through the nozzle 62 a suitable heavy coating of cement is applied thereto, the thickness of the coating being determined by a stripper 64 and a deflector 66. In drawing the strip through this apparatus, the extreme edge portions 68 of the strip are uncoated with cement, as illustratedin Fig. 4, certain parts of the apparatus, as explained in the Letters Patent above referred to, being so constructed and arranged that the marginal portions of the strip are protected from contact with the cement. Since the second coating is viscous and does not extend to the edge of the strip, the coating is not apt to flow over the edge and get on the operators table so that the stickiness and mussiness incident to the handling of a strip the coating of which extends to its edge is avoided.

A suitable length of the coated strip, say three or four feet, is drawn out upon a table 70 to give the stripa brief exposure to the air and allow the first coating to absorb solvent from the second coating, the coating material and strip being of course at normal room temperature. A ribbed insole 72 is laid, ribbed face down, on the strip 52, theend of the strip being located approximately at the breast line of the insole where the rib usually ends. The end portion of the strip 52 and the insole are grasped by the operator, a further portion of the strip drawn through the coating apparatus, and the endportion of the strip cut off substantially flush with the end of the insole 72, for example, by means of shears 74. By manipulating the insole and strip in this manner the operator obtains a hold on the strip to draw it through the cementer while avoiding contact of his fingers with the coating on the strip. The insole 72 with a piece of reinforcing material adhering to it is then turned over and the reinforcing material'is formed against the inner face of the lip 76 of the insole by suitable means, for example by employing a hand tool 78 as illustrated in Fig. 4, the reinforcing operation being. completed by trimming off the excess of reinforcing material which extends beyond the outer edge of the lip 76. For forming the reinforcing material to the lip and trimming it off I prefer to employ an insole reinforcing machine such as that disclosed in Letters Patent of the United States No. 1,726,800,,granted September 3, 1929, onapplication of Frederic E. Bertrand. In the operation of this machine, as illustrated in Fig. 5, the -.marginal portion of the insole is held between driven rolls 80, 82, the reinforcing material is tucked into the angle between the rib and the bottom of the insole by a driven roll 84, and the portion of the reinforcing material which extends beyond the outer edge of the lip is trimmed away by a rapidly rotated disk knife 86.

the trimming machine becoming gummed up withthe cement on the excess of material trimmed off by the machine. Before employing a reinforcing machine of this type, it is customary to form the reinforcing material preliminarily to the insole .by means of a hand tool such as 78, but'this hand forming step'is not essential and, under proper conditions, may be omitted.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. That improvement in methods of reinforcing insoles which comprises, applying a coating of adhesive containing substantial amountsof rubber, a resin, and a filler to a strip of reinforcing material at room temperature and substantially immediately and with the cement still at room temperature applying to each other a portion of the coated strip and an insole which is to be reinforced.

2. That improvement in methods of reinforcing insoles which comprises applying a coating of adhesive containing substantial amounts of rubber, a resin, and a filler to a strip of reinforcing material at room temperature, substantially immediately and with the cement still at room temperature applying to each other the end portion of the coated strip and an insole which is to-be reinforced, and severing the portion of the strip applied to the insole from the remainder of the strip.

3. That improvement in methods of reinforcing insoles which comprises applying a coating of adhesive containing su stantial amounts of rubber, rosin and a. filler to a strip of reinforcing fabric at room temperature,

substantially immediately and with the cement still at room temperature applying to each other the end portion of the coated fabric and the insole which is to be reinforced, and severing the portion of the strip applied to the insole from the remainder of the strip.

4. That improvement in methods of reinforcing insoles which comprises applying, at room temperature, to a strip of reinforcing material provided with a dry coating of I a cement having a substantial rubber content, a coating of adhesive containing a relatively large amount of rubber and of such a character that it will be effective even when freshly applied to cause quick adhesion of the rein-v forcing material and the material of the insole, and applying to each other, still at room temperature, a portion of the coated strip and the insole to be reinforced.

5. That improvement in methods of reinforcing leather insoles whichcomprises applying, at room temperature, to a strip of re-' nee s-as inforcing fabric provided with a d coating of a Cement having a substantial ru ber content, a coating of adhesive containing a relatively large amount of rubber and a resin, and of such a character that it will be efiective even when freshly applied to cause quick adhesion of the fabric and the leather of the insoles, and applying to each other, still at room temperature, a portion of the coated fabric and the insole to be reinforced.

6. That improvement in methods of reinforcing insoles which comprises applying a coating of adhesive containing substantial amounts of rubber, a resin, and a filler to a strip of reinforcing material at room temperature, substantially immediately and with the adhesive still at room temperature applying to each other the end portion of the coated strip and a lipped insole which is to be reinforced, severing the portion of the strip applied to the insole from the remainder of the strip, and forming the reinforcing material to the lip of the insole without; the use of heat.

7. That improvement in methods of reinforcing insoles which comprises applying a coating of adhesive containing substantial amounts of rubber, Burgundy pitch and a filler at room temperature to a strip of reinforcing material provided with a dry coating of a cement having a substantial rubber content, substantially immediately and with the adhesive still at room temperature applying to each other the end portion of the coated strip and a lipped insole to be reina; forced, severing the portion of the strip applied to the insole from the remainder of the strip, and forming the reinforcing material to the lip of the insole without the application of heat.

in In testimony whereof I have signed my name to this specification.

ELMER A. ELLIS; 

